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[摘要]：Substrate-controlled titanium-mediated aldol reactions from (S)-4-benzyloxy-3-methyl-2-butanone provide satisfactory levels of 2,5-syn asymmetric induction if they are carried out in the presence of a second equivalent of TiCl(4). Such reactions give high yields and excellent diastereoselectivity with a wide array of achiral and chiral aldehydes without needing other sources of chirality. This procedure is thus of interest for the synthesis of natural products. Furthermore, spectroscopic studies and analyses of the reacting species have revealed a possible mechanism to account for the experimental results. |
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